Select the desired themes and restart Rocview to activate them.
If you have defined your own SVG symbol for a certain item, place it in the “Setup” list before the Theme that has the default symbol.
That means the first Theme determines how a SVG is portrayed

By activating this option the normal switch positions will be shown in Cyan.2)
For active routes this color will change in Yellow.
Raster switch types are not supported by this option.
Only the SpDrS60 theme has the needed SVGs.
To get the route IDs automatically set in the switch objects the analyzer must be started again if the routes were generated with a revision older then 7884.
In case of manual routes use the Select dialog.

The following screenshot shows the usage of customized symbols comming from two themes: NL and DB:
Theme 2 can only show the unused places from theme 1, and theme 3 the unsused places from theme 1 and 2.

You can use Inkscape http://www.inkscape.org/ and start to create a new 32×32 icon.
Rocrail supports just integers for coordinated and therefore the following settings are quite useful:

These settings , especially 'Always snap', apply only during the creation of a path (Shift+F6) . As soon as you try to move path nodes with the mouse Inkscape will create decimal coordinates again.

Another useful setting is to switch on the the outline display:

At the moment the only thing evaluated in Rocrail are <path../>.
With Shift+F6 you can start this sequence; try to generate Lines only, no Curves.
As soon as you're done with the graphics save the file in Inkscape and open it with a text editor to copy the path information into another new file.

Default symbols are SVG like vector graphics, and are hardcoded in the Rocgui sources.
They only are needed when the Rocrail installation is broken, and there are only some basic symbols available! Report it if you are having trouble with symbols.